1. Field of the Invention
The present invention relates to robot tool changer technology, and more particularly, to a mechanical end-effector changer at the end of a robotic arm to be changed.
2. Description of the Related Art
Robotic arm has been widely used for industrial manufacturing. On the one hand, it can reduce the problem of decrease in product yield caused by the implementation of repetitive workflows by labor, on the other hand, it can replace human labor in harsh environmental conditions, preventing the harmful effects on the health of workers and maintaining good machining precision. However, in the manufacturing process, robotic arm must be used with an end-effector changer for allowing the robotic arm to change end-effectors (e.g. grippers, vacuum cups or drills), for processing different workpieces.
U.S. Pat. No. 6,073,512 discloses an end-effector changer entitled “Manual quick change tool changer”, which includes a master plate connected to a rotatable sprocket and a thrust bearing engaging the sprocket. This design of end-effector changer has the drawback of operational inconvenience. Further, if the thrust bearing is lost accidentally during the operation of the robotic arm, the end-effector changer is likely to cause harm to the workers. Further, U.S. Pat. No. 4,708,548 teaches the use of a manually operated rotatable member to control movement of positioning balls. When the positioning balls are engaged into respective radial bores, a first unit and a second unit are locked together. On the contrary, when the positioning balls are disengaged from the respective radial bore, the first unit and the second unit are unlocked and separable from each other. In this design, the connection strength between the first unit and the second unit is not strong enough, limiting the weight and specifications of the mating end-effectors. Further, US 2007/0235949 discloses another design of robotic tool changer that that utilizes a compressed fluid to move a piston, enabling rolling members to be actuated by the piston to lock a first unit to a second unit. When going to separate the first unit from the second unit, input the compressed fluid in the reversed direction to move the piston in direction away from the rolling members, and thus, the rolling members are permitted to move to the disengaged position. According to this prior art design, many extra equipments and arrangements (such as pipelines, storage tank, pressure pump, etc.) are necessary for the application of the compressed fluid, resulting in increased cost and causing inconvenience of the movement of the machine.